Baffle arrangement for vapor generator



y 1965 A. c. u CAUSI 3,196,843

BAFFLE ARRANGEMENT FOR VAPOR GENERATOR Original Filed Sept. 11, 1961 2Sheets-Sheet l ATTORNEY July 27, 1965 A. c. L]! CAUSI BAFFLE ARRANGEMENTFOR VAPOR GENERATOR 2 Sheets-Sheet 2 Original Filed Sept. 11. 1961 INVEN T OR.

ANTHONY C LICAUS! A TTORNEY United States Patent 3,196,843 RAFFLEARRANGEMENT FOR VAPQR GENERATOR Anthony C. Li Causi, East Brunswick,N.J., assignor to Foster Wheeler Corporation, New York, N.Y., acorporation of New York Continuation of application Ser. No. 137,154,Sept. 11, 1961. This application Sept. 21, 1964, Ser. No. 397,855 4Claims. (Cl. 122-478) This is a continuation of application Serial No.137,154, filed September 11, 1961, now abandoned.

The present invention relates to a novel baffle arrangement for watertube marine boilers and, in particular, to a tangent tube arrangementfor baffling marine boiler screen tubes for the fiow of hot gases acrossa super heater, which superheater is coextensive with an area of saidscreen tubes.

The purpose of a baffle in a marine boiler is to direct hot furnacegases over a heat-absorbing tube surface in a manner to reduce thetemperature of the gas to a minimum with a reasonably low draft loss.

In vapor generators having a superheater, a conventional marine boilerarrangement may comprise a single combustion chamber with a plurality oflaterally adjacent, vertically oriented banks of steam generating tubesextending between a steam drum and one or more water drums. Asuperheater is generally positioned between two of the banks extendingsubstantially from the front to the rear of the boiler parallel to thelongitudinal axes of the drums. A vapor generator of this type may alsohave a plurality of roof and wall tubes extending to the steam drumalong the roof of the combustion chamber. One of the banks of screentubes, generally the inner bank, i.e., the bank adjacent the combustionchamber, is bafiled in the area above the superheater to prevent furnacegases from passing to the flue without giving up heat to thesuperheater.

Conventional boiler installations for this purpose customarily usecastable refractory baffles disposed around the inner bank of screentubes, but modern high capacity, hi h temperature installations requirethat the superheater, with the necessary baffling, be moved closer tothe furnace. This results in more severe furnace conditions, and it hasbeen found that the castable refractory deteriorates or breaks up byreason of excessive movement of the screen tubes.

One approach proposed for bafiling the screen tubes above thesuperheater has been to dispose the upper portions of the screentubes'in tangent relationship. However, the tubes must be diverged fromeach other in the area of the steam drum to be accommodated in the drumsurface. It has been suggested to use fins to close the area between thediverging tubes, but this is not feasible since the width of the finswould increase to the point where they could not be adequately cooled.

According to the present invention, there is provided in a vaporgenerator a battle arrangement which overcomes the above disadvantages,and which directs the flow of hot furnace gases for most effectiveremoval of heat from the gases with minimum draft loss.

Specifically, the invention involves providing, in a marine boilerhaving a steam drum, a superheater generally below the drum, and banksof roof and screen tubes emanating from the steam drum defining in parta combustion chamber, the screen tube bank being between the combustionchamber and the superheater, a baffie arrangement in which a row oftubes of the screen tube banks are extended upwardly or disposed so asto be tangent to or come in contact with tubes of the roof tube bank ata point of tangency Or contact removed from the steam drum. The tubes ofboth banks are diverged or separated slightly from one another beforeentering the steam drum so as to be accommodated in the drum, but thescreen tubes so extended enter the drum grouped with the roof tubes sothat refractory can be poured between all of the tubes in questionsealing the area between the point of tangency and the drum.

In a direction away from the drum and away from the point of tangency,the individual tubes, which provided the tangency are themselves intangent relationship and/or otherwise bafiled to effectively completethe screen between the superheater and the drum so as to direct the flowfrom the combustion chamber across the superheater.

In describing the tubes or rows of tubes as being in tangentrelationship or in contact, it should be under stood that the tube wallsper se may be contiguous, i.e., closely spaced on normal screen tubecenters or in actual contact, or the tubes may be spaced somewhat apartfrom each other and provided with fins which are contiguous, therelationship being such as to substantially prevent the flow of gasesbetween the tubes.

It is believed that other features and advantages of the invention willbecome apparent upon further consideration of the specification andaccompanying drawings in which:

FIGURE 1 is a sectional view, in elevation, of a boiler according to theinvention;

FIGURE 2 is an enlarged sectional, elevation view of the baffilearrangement of FIG. 1;

FIGURE 3 is a fragmentary sectional view taken along line 3-3 of FIG. 2;

FIGURE 4 is a fragmentary sectional view similar to FIG. 3 of anembodiment of the invention;

FIGURE 5 is a fragmentary sectional view taken along line 55 of FIG. 1.

Referring to FIG. 1, there is illustrated a single water tube marineboiler according to the invention having a setting 10 comprising sidewalls 12 and 14, a front wall 16, a rear wall (not shown), floor 18 androof 20. A steam drum 22 is positioned adjacent the top of the boiler inroof 20, and is connected to a water drum 24 positioned at the bottom ofthe boiler in floor 18 by two banks of boiler screen tubes 26 and 28.The banks of screen tubes are disposed between a combustion chamber 30of the boiler and a flue 32. Combustion gases are provided by burners 34mounted in the front wall 16 of the setting 10.

The tube bank 26 remote from the combustion chamber, hereinafterreferred to as the outer bank, comprises a substantially greater numberof tubes than the bank 28 immediately adjacent the furnace chamber 30,which bank will be hereinafter referred to as the inner bank. Asuperheater 36, schematically shown in FIG. 1 is arranged between thetwo banks of screen tubes 26 and 28, and is disposed approximatelyintermediate the banks of screen tubes and intermediate the water andsteam drums. Roof tubes 38 are provided leading from the steam drum 22and extending downwardly along the side wall 12 to a collection manifold40 in communication with the water drum 24. Rear wall and front walltubes 42 are disposed above the roof tubes and extend from the steamdrum 22 towards the side wall 12, bending at substantially towards therear and front walls covering the walls in a conventional manner.

The superheater 36 may be conventional comprising a nest of U-shapedtubes arranged one within another lying in substantially horizontalplanes, the open ends of the U-shaped tubes extending outside of theboiler into headers which are not shown. The superheater terminates atthe base of the boiler near the water drum 24 and at the topsubstantially short of the steam drum, so that, without bathing therewould exist above the e3 superheater a passageway by which furnace gasescould pass through the inner bank 28 to the flue 32 without passingthrough the superheater 36. The present invention resides in theprovision of an improved baffle arrangement by which this by-passing offurnace gas around the superheater is prevented, or by which furnacegases are constrained to How past portions of the screen tubescoextensive with the superheater.

Referring to FIG. 2, the invention is illustrated in greater detail.

The roof tubes 38 and rear and front wall tubes 42 extend substantiallyradially from the steam drum 22 in the area immediately beneath the roof20. Spaced circumferentially from the roof and wall tubes, the innerbank of screen tubes 28 also extends radially from the steam drum asillustrated.

In a standard construction of roof and screen tubes, the main length ofthe inner bank of screen tubes is approximately perpendicular to themain length of roof and wall tubes, the screen tubes approaching theroof and wall tubes until about within one foot of the same. The screentubes are then bent at about 90 and parallel the roof and Wall tubesuntil they enter the steam drum tube sheets, while the roof and walltubes continue in a radial direction from the steam drum parallel andadjacent to the roof of the boiler.

According to the invention, rows of screen tubes of the inner bank,preferably the rows adjacent the combustion chamber, are displaced orextended upwardly from this conventional disposition and the roof tubes38 are displaced or bent downwardly until the roof tubes and screentubes are in a tangent relationship at a point 48 removed from thesurface of the steam drum.

In the embodiment illustrated in FIGS. 2 and 3, the tubes of a first row44 of the inner bank are extended until they are brought into a tangentor contiguous relationship with alternate tubes of the roof tube bank atthe point 48, while the tubes of a second row 46 of the inner bank arealso displaced or extended from their conventional disposition untilthey are in tangent relationship with the remaining tubes of the rooftube bank. In both instances, the point of tangency for the screen tubesis past that point at which the screen tubes are bent at about 90towards the steam drum. The tubes of additional rows of the inner bank,i.e. the row furthest removed from the steam drum, combustion chamber,follow their normal disposition.

To make it clear what is meant by tangent relationship, tubes defining ascreen against the flow of combustion gases will be on predeterminedcenters so as to effectively present a gas flow barrier. The screentubes 44 and 46 of the inner banks will be on the same centers at thepoint of tangency, not only with respect to each other, but also withrespect to the roof tubes 38.

Between the point of tangency and the steam drum, the displaced screentubes are grouped With the roof tubes to enter the drum more or lesswith the roof tubes.

In the area of the roof tubes between the point 48, of tangency, and thesteam drum, a castable refractory 49 is provided sealing the area aboutthe roof tubes. The refractory also flows around the screen tubesgrouped with the roof tubes, and is extended outwardly from the steamdrum into the area 50 above the roof tubes shielding the wall tubes 42from the furnace and separating the roof and wall tubes.

Refractory around the roof tubes in the area 49 conventionallywithstands severe furnace conditions. It was only refractory aroundscreen tubes, in conventional installations, that was subjected todeterioration. By the invention, it was found that grouping of thedisplaced screen tubes with the roof tubes, in effect making the screentubes part of the roof tube bank in this area adjacent the steam drum,provided the result that the re fractory around the screen tubeswithstands the movement of the tubes as well as that around the rooftubes.

From the point of tangency 48 to a second point 52 near the top of thesuperheater 36, and across the furnace from the front to the rear wall,the rows 44 and 46 of screen tubes, which are continguous with the rooftubes, are provided with fins 54 disposed between the tubes to preventthe flow of furnace gases through the screen tubes in this area. Byaligning rows 44 and 46 of the screen tubes into a single row, the finsmay be made of minimum width for adequate cooling thereof.

Below the point 52 and in the area coextensive with the superheater therows of tubes, 44 and 46, are diverged or separated from each other, asillustrated in FIG. 1, to permit the free passage of air past the tubes.This is also illustrated in FIG. 5 which shows the screen tubes 44 and46 in the area above the superheater in alignment or defining a baffiesurface with fins 54 closing the gaps between the tubes, and the tubes46 in the area below the point 52 diverging from the tubes 44 towardsthe combustion chamber.

It should be noted that the section line 3-3 is taken along a brokenline to show the fins 54 bridging the gaps between the tubes 44 and 46,and to show the castable refractory 49 disposed around the roof tubes38. The refractory 49 is preferably poured into place to effectivelyclose off any passageways for the flow of gases (at the point oftangency 48) between the fin surfaces 54 and the refractory 50. Byoff-setting the screen tubes 44 and 46 from the roof tubes 33, a moreeffective baffling is obtained since the castable refractory 49 can bepoured close to the fins 54 at the point of tangency.

Instead of using fins, the screen tubes themselves may be contiguouswith each other in the area between the point of tangency 48 and thesuperheater to provide baffling. This arrangement is illustrated in FIG.4 showing the tubes 44 and 46 as closely spaced and without fins.

It is apparent from the above description that the invention eliminatesthe need for bathing of the screen tubes in the area between the point48 of tangency and the steam drum, and provides a bafile surface abovethe superheater defined by the tangent screen tubes 44 and 46, the pointof tangency 48, the tangent roof tubes 38, and the refractory material49 and 50, by which the furnace gases are constrained to pass throughthe screen tubes in an area coextensive with the superheater and areprevented from by-passing the superheater.

Various modifications will be apparent to those skilled in the art. Forinstance, the invention is readily applicable to types of boilers otherthan the specific type described and shown in the drawings. Accordingly,the present invention is to be limited only as defined in the followingclaims.

What is claimed is:

1. A vapor generator comprising a combustion chamber, an upper steamdrum, a bank of roof tubes and at least one bank of steam generatingscreen tubes entering said steam drum, a superheater co-extensive withat least a portion of said bank of screen tubes, said superheater andscreen tubes being arranged such that the screen tubes shield saidsuperheater from said combustion chamber, said roof and screen tubesbeing disposed whereby tubes of said bank of roof tubes are in tangentcontiguous offset relationship and on a triangular pitch with tubes ofsaid bank of screen tubes and nested into the spacing between the latterat a point of tangency removed from said steam drum, the screen tubesbeing contiguous to each other at said point of tangency, the roof tubesand screen tubes tangent thereto being in grouped and triangularrelationship between the point of tangency and the steam drum, acastable refractory poured into the spacing around the roof tubes andbetween the roof and screen tubes at the point of tangency to the steamdrum sealing the area around said bank of roof tubes and the screentubes against the flow of combustion gases between said point oftangency and the steam drum, said screen tubes which are tangent to saidroof tubes also being tangent to each other from said point of tangencyto a second point adjacent said superheater to provide a bafiie surfacewhereby hot furnace gases from said combustion chamber are constrainedto flow past portions of said screen tubes coextensive with saidsuperheater.

2. A vapor generator according to claim ll, wherein said roof tubes arebafiied from said point of tangency across the roof of said combustionchamber.

3. A vapor generator according to claim 1, and includ ing fins betweenthe screen tubes from said point of tangency to said second pointadjacent said superheater.

4. A vapor generator comprising a combustion chamher, a substantiallyhorizontal upper steam drum, a substantially horizontal water drumdisposed below said steam drum, multiple banks of upright steamgenerating screen tubes disposed adjacent said chamber and extending between said steam drum and said water drum, one of said banks having abent construction including upper and lower approximately horizontalruns and a substantially vertical run therebetween defining with anotherof said upright banks a space between the steam drum and said waterdrum, a superheater disposed in said space, a bank of roof tubesentering said steam drum in a direction approximately parallel to saidupper run of said bank of bent screen tubes, said upper run of saidscreen tubes and the bank of roof tubes being arranged whereby tubes ofone are disposed in tangent contiguous offset relationship and on atriangular pitch with tubes of the other and nested into the spacingdefined by the latter at a point of tangency removed from the steamdrum, the screen tubes which are tangent to said roof tubes also beingtangent to each other at said point of tangency and from said point oftangency to a second point further removed from the steam drum andadjacent to the superheater to provide a bathe surface whereby hotfurnace gases from the combustion chamber are constrained to flow pastportions of said screen tubes co-extensive with the superheater, theroof tubes and screen tubes tangent thereto being in grouped andtriangular relationship between the point of tangency and the steamdrum, a castable refractory poured into the spacing around the rooftubes and between the roof and screen tubes at the point of tangency tothe steam drum sealing the area around said bank of roof tubes and thescreen tubes against the flow of combustion gases between said point oftangency and the steam drum.

References ited by the Examiner UNITED STATES PATENTS 2,206,265 7/40Saathofi 122-235 2,327,161 8/43 Badenhausen l22--473 2,834,327 5/58Banker 122510 FREDERICK L. MATTESON, 1a., Primary Examiner. KENNETH W.SPRAGUE, Examiner.

1. A VAPOR GENERATOR COMPRISING A COMBUSTION CHAMBER, AN UPPER STREAMDRUM, A BANK OF ROOF TUBES AND AT LEAST ONE BANK OF STREAM GENERATINGSCREEN TUBES ENTERING SAID STREAM DRUM, A SUPERHEATER CO-EXTENSIVE WITHAT LEAST A PORTION OF SAID BANK OF SCREEN TUBES, SAID SUPERHEATER SAIDSCREEN TUBES BEING ARRANGED SUCH THAT THE SCREEN TUBES SHIELD SAIDSUPERHEATER FROM SAID COMBUSTION CHAMBER, SAID ROOF AND SCREEN TUBESBEING DISPOSED WHEREBY TUBES OF SAID BANK OF ROOF TUBES ARE IN TANGENTCONTIGUOUS OFFSET RELATIONSHIP AND ON A TRIANGULAR PITCH WITH TUBES OFSAID BANK OF SCREEN TUBES AND NESTED INTO THE SPACING BETWEEN THE LATTERAT A POINT OF TANGENCY REMOVED FROM SAID STEAM DRUM, THE SCREEN TUBESBEING CONTIGUOUS TO EACH OTHER AT SAID POINT OF TANGENCY, THE ROOF TUBESAND SCREEN TUBES TANGENT THERETO BEING IN GROUPED AND TRIANGULARRELATIONSHIP BETWEEN THE POINT OF TANGENCY AND THE STEAM DRUM, ACASTABLE REFRACTORY POURED INTO THE SPACING AROUND THE ROOF TUBES ANDBETWEEN THE ROOF AND SCREEN TUBES AT THE POINT OF TANGENCY TO THE STEAMDRUM SEALING THE AREA AROUND SAID BANK OF ROOF TUBES AND THE SCREENTUBES